Many kinds of anti-allergic drugs have been utilized for treatment of allergic diseases.
Among these drugs, the release-inhibitors of allergic chemical mediators have been widely used as the drugs for causal treatment.
More recently the inhibitors of immunoglobulin E (hereinafter referred to as IgE) antibody formation have been receiving attention as prospective drugs for causal treatment, since IgE has been confirmed to be primarily responsible for pathogenesis of type I allergic diseases.
Several classes of immunoglobulin(s) [hereinafter referred to as Ig(s)] are well known as antibodies concerned with immune response. Most of Igs, especially immunoglobulin G (hereinafter referred to as IgG) which is one class of Igs, play an important role in self-defense mechanisms in mammals against foreign substances such as viruses, bacteria, tumors and the like. However, IgE has been confirmed to be primarily responsible for diseases such as allergic bronchial asthma, allergic rhinitis, atopic dermatitis, hypersensitiveness, and the like.
Therefore, selective inhibition of IgE formation might be an effective pharmacological approach for the treatment of allergy in the human. And attempts have been widely made to develop the selective inhibitors of IgE formation. The prospective inhibitors preferably would not inhibit excessively any class of Igs except IgE for reasons mentioned above.
Up to the present time, various compounds have been reported to inhibit IgE formation in literature such as Japanese Patent Application (OPI) Nos. 130516/79 and 76/87 (the term "OPI" used herein refers to an unexamined Japanese patent publication); U.S. Pat. Nos. 4,395,405 and 4,691,018; British Patent Application No. 2,020,665 (A) and J. Med. Chem. Vol. 25, No. 12, pages 1495-1499, 1982.
However, these compounds reported above as an inhibitor of IgE formation have been confirmed to exhibit less selectivity and have not been applicable yet.